A master thesis from Aalborg University
Inverse Parameter Identification for Multilinear Cohesive Laws
Author(s)
Term
4. term
Education
Publication year
2017
Submitted on
2017-06-02
Pages
128 pages
Abstract
Through this report a methodology for characterization of fracture related parameters for numerical modelling of delamination in composite materials is developed. The methodology relies on concepts of inverse parameter identification and optimization techniques. The numerical modelling is done through use of the finite element method and cohesive zone modelling. An experiment is simulated in a parametric finite element model and a residual is defined as the discrepancy in some given response from the numerical model and the physical experiment. The parameter identification is then done by minimization of the residual. The crack propagation is modelled using user-defined interface elements through ANSYS. A mixed mode multilinear cohesive law for the user-defined interface element is developed for this purpose. Since the parameter identification is based on optimization techniques, much time is spent on formulating a proper objective function. Initially, the objective function is based on global structural response, but use of local measurements in the fracture process zone is also investigated. The motivation for this method is to reduce usual assumptions involved in characterization of cohesive zone parameters, increase the practical applicability by not limiting the approach to coupon testing, and gain as much information from few but costly experiments.
Keywords
Documents
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